globalchange  > 过去全球变化的重建
DOI: 10.1016/j.quascirev.2015.07.028
Scopus记录号: 2-s2.0-84949225777
论文题名:
Orbital forcing of glacial/interglacial variations in chemical weathering and silicon cycling within the upper White Nile basin, East Africa: Stable-isotope and biomarker evidence from Lakes Victoria and Edward
作者: Cockerton H.E.; Street-Perrott F.A.; Barker P.A.; Leng M.J.; Sloane H.J.; Ficken K.J.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2015
卷: 130
起始页码: 57
结束页码: 71
语种: 英语
英文关键词: Biomarkers ; Diatoms ; Lake Edward ; Lake Victoria ; Late Quaternary ; Oxygen isotopes ; Silicon cycle ; Silicon isotopes ; White Nile
Scopus关键词: Algae ; Aquatic ecosystems ; Biogeochemistry ; Biomarkers ; Carbon ; Catchments ; Dissolution ; Ecology ; Geochemistry ; Glacial geology ; Isotopes ; Lakes ; Phytoplankton ; Plants (botany) ; Rain ; Silica ; Silicates ; Silicon ; Diatoms ; Lake Victoria ; Late quaternary ; Oxygen isotopes ; Silicon cycle ; Silicon isotopes ; White Nile ; Weathering ; algae ; Bacillariophyta ; Embryophyta ; Tracheophyta
英文摘要: On Quaternary time scales, the global biogeochemical cycle of silicon is interlocked with the carbon cycle through biotic enhancement of silicate weathering and uptake of dissolved silica by vascular plants and aquatic microalgae (notably diatoms, for which Si is an essential nutrient). Large tropical river systems dominate the export of Si from the continents to the oceans. Here, we investigate variations in Si cycling in the upper White Nile basin over the last 15 ka, using sediment cores from Lakes Victoria and Edward. Coupled measurements of stable O and Si isotopes on diatom separates were used to reconstruct past changes in lake hydrology and Si cycling, while the abundances of lipid biomarkers characteristic of terrestrial/emergent higher plants, submerged/floating aquatic macrophytes and freshwater algae document past ecosystem changes. During the late-glacial to mid-Holocene, 15-5.5 ka BP, orbital forcing greatly enhanced monsoon rainfall, forest cover and chemical weathering. Riverine inputs of dissolved silica from the lake catchments exceeded aquatic demand and may also have had lower Si-isotope values. Since 5.5 ka BP, increasingly dry climates and more open vegetation, reinforced by the spread of agricultural cropland over the last 3-4 ka, have reduced dissolved silica inputs into the lakes. Centennial-to millennial-scale dry episodes are also evident in the isotopic records and merit further investigation. © 2015 The Authors.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59749
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作者单位: Department of Geography, College of Science, Swansea University, Swansea, United Kingdom; Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom; NERC Isotope Geosciences Facilities, British Geological Survey, Nottingham, United Kingdom; Centre for Environmental Geochemistry, School of Geography, University of Nottingham, Nottingham, United Kingdom

Recommended Citation:
Cockerton H.E.,Street-Perrott F.A.,Barker P.A.,et al. Orbital forcing of glacial/interglacial variations in chemical weathering and silicon cycling within the upper White Nile basin, East Africa: Stable-isotope and biomarker evidence from Lakes Victoria and Edward[J]. Quaternary Science Reviews,2015-01-01,130
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